218 MISC. PUBLICATION 423, U. S. DEPT. OF AGRICULTURE 



8. Lower surface of the leaf blades decidedly paler than the upper, usually 

 glaucous (10). 

 10. Leaf blades all, or some of them, conspicuously and sharply long-acumi- 

 nate at apex; stamens 3 or more; filaments hairy toward the base; 

 usually trees (11). 

 11. Petioles slender, those of the larger leaves usually 10 mm. long or 

 longer; blades commonly not more than 3 times as long as wide, 



not shiny above 10. S. amygdaloides. 



11. Petioles stout, usually less than 10 mm. long; blades commonly at 

 least 4 times as long as wide, often shiny above (12) . 

 12. Margins of the leaf blades and the petioles near the apex bearing 

 conspicuous yellowish glands; branchlets and the upper surface 



of the leaf blades very shiny 11. S. lasiandra . 



12. Margins of the leaf blades and the petioles not or not conspicu- 

 ously glandular; branchlets and the upper surface of the leaf 

 blades not or only moderately shiny (13). 

 13. Leaf blades commonly broadly lanceolate (less than 6 times as 

 long as wide) , usually only moderately acuminate, glaucous 

 but ordinarily not silvery white beneath. 7. S. laevigata. 

 13. Leaf blades commonly narrowly lanceolate (6 or more times 

 as long as wide), very long- and sharp-acuminate, silvery 



white beneath 12. S. bonplandiana. 



10. Leaf blades acute or short-acuminate at apex (14). 



14. Bases of the leaf blades rounded or subcordate (seldom cuneate) ; 

 stamens 2, the filaments glabrous (15). 

 15. Bark of the twigs yellow or brown; leaf blades oblong-lanceolate 

 to linear-lanceolate, yellowish green and usually not glossy 

 above, moderately glaucous beneath 13. S. lutea. 



15. Bark of the twigs reddish brown to plum-colored; leaf blades 



elliptic (often broadly so), dark green and slightly glossy 

 above, strongly glaucous beneath; stipules large, usually per- 

 sistent 14. S. PSEUDOMONTICOLA. 



14. Bases of the leaf blades cuneate or attenuate (sometimes rounded in S. 

 laevigata), the blades often shiny above and very glaucous 

 beneath (16). 



16. Branchlets commonly dark purple (plum-colored) and very 



glaucous; a shrub, up to 4 meters high 5. S. irrorata. 



16. Branchlets yellow to dark brown, not or but slightly glaucous; 

 usually trees (17). 

 17. Leaf blades prevailingly oblanceolate; stamens 2, the filaments 



glabrous 6. S. lasiolepis. 



17. Leaf blades prevailingly lanceolate or oblong-lanceolate; 

 stamens more than 2, the filaments hairy toward the base. 



7. S. LAEVIGATA 



1. Salix taxifolia H. B. K., Nov. Gen. et Sp. 2: 22. 1817. 

 Cochise, Santa Cruz, and Pima Counties, 3,500 to 6,000 feet, along 



streams and washes in the foothills. Western Texas to Arizona, 

 south to Guatemala. 



Yewleaf willow. A relatively slow-growing large shrub or tree, 

 attaining a height of 12 m. (40 feet) and a trunk diameter of 45 cm. 

 (18 inches), but in Arizona usually much smaller, affording excellent 

 browse for livestock. 



2. Salix exigua Nutt., North Amer. Sylva 1: 75. 1842. 



Almost throughout the State, up to 7,000 feet, along streams. 

 Saskatchewan to British Columbia, south to northern Mexico. 



Coyote willow. Usually a shrub and not more than 4.5 m. (15 

 feet) high, often forming thickets. A very narrow-leaved form 

 (var. stenophylla (Rydb.) Schneid.), and a less pubescent form with 

 relatively broad leaves (var. virens Rowlee), are found here and there 

 in Arizona. What may be an undescribed variety is reported from 

 the Baboquivari Mountains. (See footnote 29, p. 216, Goodding, 

 pp. 2, 5.) 



